Pressure transducers are located in the tiny holes visible on the engine inlet lip of NASA's F-18 High Alpha Research Vehicle (HARV). The sensors in this photo are located at the top of the inlet duct entrance and measure pressure distortions during flight. The highly modified F-18 airplane flew 383 flights at the Dryden Flight Research Center in Southern California, over a nine year period and demonstrated concepts that greatly increase fighter maneuverability. Among concepts proven in the aircraft is the use of paddles to direct jet engine exhaust in cases of extreme altitudes where conventional control surfaces lose effectiveness. Another concept, developed by NASA Langley Research Center, is a deployable wing-like surface installed on the nose of the aircraft for increased right and left (yaw) control on nose-high flight angles.